Manufacturing grids



Sept- 1959 v A. A. BROOKE 2,906,299

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2,906,299 Patented Sept. 29, 1959 dice MANUFACTURING GRIDS Arthur Alan Brooke, Toronto, Ontario, Canada, assignor to Canadian General Electric Company, Limited, Toronto, Ontario, Canada, a corporation of Canada Application March 5, 1954, Serial No. 414,372

Claims priority, application Canada April 15, 1953 3 Claims. (Cl. 140-715) My invention relates to apparatus for the manufacture of wound grids for electron discharge devices.

The grids commonly used in electron discharge tubes consist of a helix of wire wound on one or more metallic support rods extending lengthwise of the helix to which rod the turns of the helix are anchored and in which the ends of the support rods extending beyond the helix are used to locate the grid accurately in the supporting structure which is commonly one or more mica discs with holes punched therein for locating the grids and other electrodes.

Automatic machines have been devised for the manufacture of such grids in which the support wires are fed forwardly continuously to a rotatable winding head which notches them, feeds the grid Wire into the notches and then deforms the metal of the support rods anchoring the turn of the grid wire thereto. As the grids are relatively short it has been the practice for economical manufacture to wind a strip of considerable length convenient for handling, which strip is later cut up into a plurality of grids. The cut grids are then individually shaped to their final form by pressing in dies which step is necessary particularly when the contour of the desired grid does not adapt itself to the direct formation in the winding operation.

My invention relates to a means of manufacturing whose main benefit resides in economy of manufacture of grids of the type described and an understanding of my invention will be had from a consideration of the following detailed description taken together with the accompanying drawings in which Fig. 1 is an elevational view showing a strip of grid formed by an automatic machine;

Figs. 2, 3, 4 and are cross-sections of grids illustrative of the practice of my invention;

Fig. 6 is a side elevational view drawn to a reduced scale, of the apparatus constructed in accordance with an embodiment of my invention;

Fig. 7 is a cross sectional view, partly in elevation, of the apparatus taken along the line VII-VII of Fig. 6; and

Figs. 8 and 9 are fragmentary enlarged views illustrative of typical roller die shapes useful in my invention.

Referring to the drawings Fig. 1 represents a strip of grid formed by any suitable well-known type of automatic grid winding machine (not shown) and consists of support rods 3 on which are helically wound a fine wire 2, the turns thereof being anchored to the outer sides of the support rods as by notching and peening. In the operation of the machine the rods 3 are fed forward lengthwise and the grid wire 2 fed from spools is wrapped around them, the outer side of each side rod being notched to receive the wire and then peened mechanically to lock the wire thereto. When a strip of convenient length for handling is completed it is cut off and removed from the winding machine. As the strip is to be subdivided into individual grid lengths it is customary to adjust the machine whereby a plurality of turns of wire adjacent the point at which the strip is to be out are not anchored to the side rods so as to facilitate stripping of some of the turns from the rods. In the strip illustrated in Fig. 1 the points at which it is to be out are indicated at 4 and the wires 3 adjacent these points as indicated by 5 are not anchored.

The customary practice in the manufacture of grids is to ma. strips such as illustrated in Fig. 1 of convenient length for handling as above described and then cut them into grid lengths. Each grid is then dealt with separately, the unwanted grid wires unwound and cut off and each grid is individually formed to final shape.

In accordance with my invention, I pass the strip as it comes from the machine, and before cutting into grid lengths, through shaping rollers which form the entire strip to the shape desired, such for example as shown in Figs. 3 and 5 and then cut the strip of shaped grid stock into individual grids. The shaping rollers may be mounted on or adjacent to the winding machine and can be easily attended to by the same operator.

In Fig. 3 I have shown a cross section of a grid of circular configuration in which the spacing of the grid wire 2 from a cylindrical cathode 6 located at its axis is uniform throughout its circumference. Obviously as the winding operation above described attaches the grid wire 2 to the outer sides of the rods 3 such a grid cannot, be wound to final form directly in the winding machine. This grid is first wound in strips in the regular manner described whereby it has a configuration such as shown in Fig. 2. Here, it will be observed, the support rods 3 are disposed within the space defined by the wire 2 and thus tend to destroy the uniform distribution of the wire 2 relative to the cathode 6 (Fig. 3). In accordance with my invention, the strip as it comes from the machine is passed through appropriate roller dies whereby the entire strip is deformed to its desired final configuration shown in Fig. 3 and then the strip is cut into individual grid lengths.

In Figs. 4 and 5 I have shown another grid construction which requires a separate forming operation after being wound on the winding machine. In this case the sides of the grid are more closely spaced from one another than the diameter of the side rods 3 on which they are wound. Here again, the final form of the grid (Fig. 5) desirably includes substantially no part ofthe support rods 3 in the space betweenv the substantially parallel wires 2.

In Figs. 6 and 7 I have illustrated apparatus suitable for the practice of my invention. As shown, the apparatus comprises a base 7 having a block 8 secured to or forming part of the base 7, the block 8 having a pair of bearings 9 adapted to support a roller die 10 for rotation. A block 11 carrying a roller die 14 in bearings 13 is mounted on the base 7 in a way 12 whereby it may be adjusted towards and away from the block 8 to vary the spacing between the rollers 10 and 14. A member 15 forming one side of the way 12 may be adjusted by means of a clamping lever 16 to release the block 11 for adjustment and to clamp it in desired adjusted position. A member 17, secured to the base carries a micrometer screw 18 with a knob 19, which screw 18 is in engagement with the block 11 whereby precise setting of the block may be had by adjusting the knob. A dial indicator 20 is mounted on a member 21 projecting fromthe base. A rod 22 is mounted on the block 11 and passes freely through a hole provided in the block 8 to engage the indicator 20 whereby the setting of the block may be conveniently observed on the dial. A vertically extending guide 25 is mounted on the base and has a chute 23 of a size loosely to receive the particular grid strips being treated and leading to the roller dies 10 and 14. An opening 24 is provided in the base opposite the lower e 3 end of the chute 23 through which the grid strips can pass after being formed by the roller dies 10 and 14.

Figs. 8 and 9 show, by way of example, roller die shapes that can be employed to practice my invention. Thus, in Fig. 8, the roller dies 10 and 14 to form grids as shown in Fig. 3, are provided with rims that are formed to define centrally disposed, substantially semicircular grooves 26 and 27, respectively, the diametral ends of which are provided with substantially smaller grooves 28 and 29, respectively, which preferably are spaced a small distance closer together than the normal spacing of the rods 3 as the strip comes from the winding machine. It will thus be seen that when the strip is passed between the rollers the rods 3 are engaged in the space defined by the opposed grooves 28 and 29 and are slightly urged toward each other, thereby causing the wire 2 to be pressed outwardly to engage the circular wall of the grooves 26 and 27.

In Fig. 9, roller dies 10' and 14' to form grids of the type illustrated in Fig. 5, can be formed with substantially flat-bottom grooves 30 and 31, respectively, which are provided at the ends with substantially semicircular grooves 32 and 33, respectively, which may be disposed a somewhat larger distance apart than the normal spacing of the rods 3 of the grid strip as it comes from the winding machine. Thus, when the strip is fed between the roller dies 10' and 14' the rods3 are engaged in the space between the grooves 32 and 33 and are thereby urged somewhat farther apart,. whereby the wire 2 is drawn tightly and made to conform to the parallel sides of the space defined by the grooves 30 and 31.

In operation, a strip of grids having cross-sections such as illustrated in Figs. 2 or 4 as it comes from the winding machine is fed by the operator into the upper end of the chute 23 which guides it between the opposing faces of the roller dies 10 and 14 whose surfaces are configured as shown in Figs. 8 or 9 to press the wires 2 of the strips to deform the same thus to produce the final form illustrated in Figs. 3 or 5, respectively. The strip is pushed through the rollers and when the lower end of the deformed strip passes through the hole 24 in the base 7 the lower end may be grasped and the pass completed. The strip of grids in their formed shape is now cut into individual grids.

The method of my invention results in substantial savings in costs compared with the previous methods.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A grid-forming machine comprising means for guiding a strip of grid wire to a forming station, said strip normally including a pair of laterally spaced elongated wire supports about which the wire is wound with a substantial part of said supports being contained within the space defined by said wire, a pair of roller dies mounted at said station and arranged to receive said strip between cooperating peripheral surfaces thereof, said cooperative surfaces each including a laterally spaced pair of peripheral grooves for receiving the wire supports and cooperating with the grooves of the other surface for forming the side portions of said wire about said supports and the grooves of each of said pairs being spaced slightly differentially relative to the original spacing of said supports for laterally moving said wire supports and thereby altering the original spacing therebetween thereby to alter the shape of the portions of said wire intermediate said supports.

2. The machine as defined in claim 1 wherein said peripheral surfaces each include peripheral grooves larger than and interposed between the support-receiving grooves and said support-receiving grooves are spaced closer than the original spacing of said wire supports to reduce the spacing between the wire supports as said str-ip passes between said roller dies and the closer spacing between said wire supports is effective to cause the intermediate portions of said wire to bow outwardly into conforming engagement with said larger grooves.

3. The machine as defined in claim 1 wherein die surfaces are interposed between the grooves of each of said pair of support-receiving grooves and said support-receiving grooves are spaced wider than the original spacing between said wire supports to increase the space between the wire supports as said strip is passed between said roller dies, thereby to cause said intermediate portions of said wire to be drawn into conforming engagement with said die surfaces between said grooves.

References Cited in the file of this patent UNITED STATES PATENTS 1,123,616 Stewart Jan. 5, 1915 1,510,704 Rendleman Oct. 7, 1924 1,691,134 Schlaich Nov. 13, 1928 1,727,184 Thompson Sept. 3, 1929 1,980,937 Dodge Nov. 13, 1934 1,987,333 Geer Jan. 8, 1935 2,000,163 Clark May 7, 1935 2,036,034 Fulmer Mar. 31, 1936 2,181,288 Washburn Nov. 28, 1939 2,586,629 Englert Feb. 19, 1952 2,680,208 Gehrke June 1, 1954 2,759,499 Gartner Aug. 21, 1956 

